There are three subtypes of the disorder which consist of it being predominantly inattentive (ADHD-PI or ADHD-I), predominantely hyperactive-impulsive (ADHD-HI or ADHD-H), or the two combined (ADHD-C). Often people refer to ADHD-PI as "attention deficit disorder" (ADD), however, the latter has not been officially accepted since the 1994 revision of the DSM. ADHD impacts school-aged children and results in restlessness, acting impulsively, and lack of focus which impairs their ability to learn properly.

It is the most commonly studied and diagnosed psychiatric disorder in children, affecting about 3 to 5 percent of children globally[4][5] and is diagnosed in about 2 to 16 percent of school-aged children.[6] It is a chronic disorder[7] with 30 to 50 percent of those individuals diagnosed in childhood continuing to have symptoms into adulthood.[8]

ADHD management usually involves some combination of medications, behavior therapy, lifestyle changes, and counseling. Only children with severe ADHD symptoms should be considered for medication as a first-line treatment option. Medication therapy can also be considered for those with moderate ADHD symptoms who either refuse psychotherapeutic options or else fail to respond to psychotherapeutic input.[16]:p.317

ADHD and its diagnosis and treatment have been considered controversial since the 1970s.[17] The controversies have involved clinicians, teachers, policymakers, parents and the media. Topics include ADHD's causes, and the use of stimulant medications in its treatment.[18][19] Most healthcare providers accept ADHD as a genuine disorder—debate in the scientific community centers mainly around how it is diagnosed and treated.[20][21][22]